package Array;

/**
 * 122.best-time-to-buy-and-sell-stock-ii
 * https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/description/
 *
 * Say you have an array for which the ith element is the price of a given stock on day i.
 *
 * Design an algorithm to find the maximum profit.
 * You may complete as many transactions as you like (i.e., buy one and sell one share of the stock multiple times).
 *
 * Note: You may not engage in multiple transactions at the same time (i.e., you must sell the stock before you buy again).
 *
 * Example 1:
 *
 * Input: [7,1,5,3,6,4]
 * Output: 7
 * Explanation:
 * Buy on day 2 (price = 1) and sell on day 3 (price = 5), profit = 5-1 = 4.
 *              Then buy on day 4 (price = 3) and sell on day 5 (price = 6), profit = 6-3 = 3.
 *
 * Example 2:
 *
 * Input: [1,2,3,4,5]
 * Output: 4
 * Explanation:
 * Buy on day 1 (price = 1) and sell on day 5 (price = 5), profit = 5-1 = 4.
 *              Note that you cannot buy on day 1, buy on day 2 and sell them later, as you are
 *              engaging multiple transactions at the same time. You must sell before buying again.
 *
 * Example 3:
 *
 * Input: [7,6,4,3,1]
 * Output: 0
 * Explanation:
 * In this case, no transaction is done, i.e. max profit = 0.
 */
public class E_122_买卖股票的最佳时机2 {

    /**
     * 贪心算法
     * 只要今天价格小于明天价格就在今天买入然后明天卖出
     */
    public static int maxProfit(int[] prices) {
        int length = prices.length;
        int profit = 0;
        for (int i = 1; i < length; i++) {
            if (prices[i] > prices[i-1]) {
                System.out.println(prices[i]);
                profit += prices[i] - prices[i-1];
            }
        }
        return profit;
    }

    public static void main(String[] args) {
//        System.out.println(maxProfit(new int[]{7,1,5,3,6,4}));
        System.out.println(maxProfit(new int[]{1,2,3,4,5}));
//        System.out.println(maxProfit(new int[]{7,6,4,3,1}));
    }
}
